ObjectId generate mongodb ObjectId, currently, just use mgo.v2 lib, can write self.

ObjectIdWithNow generate ObjectId with now, currently, just use mgo.v2 lib, can write self.

RandomUUID Version 4, based on random numbers (RFC 4122).

SimpleRandomUUID simple RandomUUI base RandomUUID.

UnixMillisId generate timestamp id with millisecond.

UnixNanoTimeId generate timestamp id with unixNano.

UUIDV1 Version 1, based on timestamp and MAC address (RFC 4122).

UUIDV2 Version 2, based on timestamp, MAC address and POSIX UID/GID (DCE 1.1).

UUIDV3 Version 3, based on MD5 hashing (RFC 4122).

UUIDV5 Version 5, based on SHA-1 hashing (RFC 4122).